Combustion initiation system

ABSTRACT

A combustion initiation system includes an initiating device for producing, containing and propelling a combustion initiating plasma having an energy density approaching that produced by combustion of the fuel itself, and is suitable for initiating combustion in relatively lean mixtures of various types of fuels. A high voltage power supply delivers electrical energy by a coaxial cable to the initiating device which communicates with a fuel mixture in a combustion area such as the combustion chamber of an ordinary internal combustion engine. The initiating device includes a capacitive portion for storing a large quantity of electrical energy therein derived from the power supply, and an electrode portion integral with the capacitive portion which comprises a pair of concentric, rod shaped electrodes for producing a high energy, umbrella shaped plasma discharge, using the inverse pinch technique. Due to the close proximity between the capacitive and electrode portions of the initiating device, rapid energy transfer from the former to the latter creates high magnetic pressures which transform the discharge into a high energy plasma jet which is delivered well into the combustion area.

TECHNICAL FIELD

This invention generally deals with combustion of fuels, especially ininternal combustion engines, and relates more particularly to a deviceimplemented method of improving combustion using high energy plasmainitiation techniques.

BACKGROUND ART

Conventional internal combustion engines, such as those used in motorvehicles, have long employed spark producing systems for initiatingcombustion of fuels within combustion cylinder chambers. Although "sparkplug" type devices for initiating fuel combustion have gained almostuniversal use in the past, it has been known that these devices were notparticularly efficient in maximizing fuel combustion, hence, additionalfuel was required to achieve a desired level of power output; moreover,incomplete fuel combustion resulted in the production of air pollutantswhich had to be dealt with. In order to assure satisfactory operation,prior art spark plug devices have required that the spark dischargeproduced thereby communicate with a region within the combustion chamberwhere an optimum (stoichiometric) fuel-to-air mixture exists, since theresulting energy density of combustion from a stoichiometric regionwithin the chamber is usually high enough to ensure that the remainderof the fuel achieves combustion. Inasmuch as the energy produced by thespark discharge is insufficient to induce combustion of fuel-to-airmixtures which are not stoichiometric, richer mixtures of fuel to airwere required in the past in order to assure that the spark dischargereached a stoichiometric region within the combustion chamber. However,due to the limited volume within the chamber which might be reached by aspark discharge, stoichiometric values of fuel to air mixtures could notalways be provided under cold starting, idling, or part load operatingconditions.

Because of the problems discussed above related to the relatively lowenergy produced by spark discharge systems, numerous attempts have beenmade in the past to increase the energy delivered by the sparkdischarge, and various prior art spark plug improvements are alleged toyield a "hotter spark", but none of such prior art spark plug devicesare in fact capable of delivering the level of power needed to producerelatively complete combustion of fuel to air mixtures which are lessthan stoichiometric.

Ignition devices for producing an ignition plasma, such as thatdisclosed in U.S. Pat. No. 3,842,818, have been devised in an effort toincrease the level of energy delivered to the fuel to air mixture, butthe energy levels achieved by these plasma producing devices have notbeen sufficient to initiate combustion in fuel-to-air mixtures which arerelatively far from stoichiometric, and therefore achieved satisfactoryresults only when a stoichiometric region of such fuel-to-air mixturewas in proximity to the ignition plasma.

Another prior art attempt at solving the problem involves providing acombustion chamber physically configured to produce stratification ofthe fuel-to-air therewithin, whereby the richer mixtures are producedmixtures in a region immediately adjacent a conventional spark dischargeinitiating device, thereby assuring that the initiating spark reaches aregion of fuel-to-air mixture which is close to stoichiometric.

SUMMARY OF THE INVENTION

The present invention provides a combustion initiation system whichincludes an initiating device that produces an initiation plasma with anenergy density comparable to that produced by combustion of the fuel inthe chamber, in order to initiate combustion in fuel-to-air mixtureswhich are relatively far from stoichiometric, thereby allowing the useof leaner fuel-to-air mixtures for improving operating economy whilealso reducing hydrocarbon emissions. The initiation system also includesa high voltage pulsed power supply for delivering electrical energy bymeans of a coaxial cable to the initiating device which communicateswith the combustion chamber. The initiating device includes a capacitiveportion for storing alarge quantity of electrical energy therein derivedfrom the pulsed power supply and an electrode portion coupled to thecapacitive portion which comprises a pair of concentric electrodes forproducing a high energy plasma discharge, using the inverse pinchtechnique. The discharge is transformed by high magnetic pressures into.[.a.]. .Iadd.an outwardly propelled, inverse .Iaddend.linear pinchdischarge forming a high energy plasma jet that is linearly deliveredwell into the combustion chamber. Exceptionally high levels of powerinherent in the plasma jet are achieved in part by the close proximitybetween the electrode portion and capacitive portion which allows rapidtransfer of the stored energy to the former from the latter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which form an integral part of the specification andare to be read in conjunction therewith, and in which like numerals areemployed to represent like parts in the various views;

FIG. 1 is a simplified block and schematic diagram of a combustioninitiation system which forms the present invention;

FIG. 2 is an end view of one form of a combustion initiating device usedin conjunction with the initiation system shown in FIG. 1;

FIG. 3 is a longitudinal sectional view taken along line 3--3 in FIG. 2;

FIG. 4 is a longitudinal sectional view of another form of combustioninitiating device suitable for use in conjunction with the initiationsystem shown in FIG. 1;

FIG. 5 is a view of one end of a combustion initiating device suitablefor use in conjunction with the initiation system shown in FIG. 1;

FIG. 6 is a longitudinal sectional view of the device depicted in FIG.5;

FIG. 7 is a view of the other end of the device depicted in FIG. 5;

FIG. 8 is a detailed, longitudinal sectional view, taken on a largerscale, of the tip portion of the device depicted in FIGS. 5-7 which isalso suitable for use in connection with the devices shown in FIGS. 2-4;

FIG. 9 is a detailed, longitudinal sectional view of an alternate tipportion design suitable for use in connection with any of the devicesdepicted in FIGS. 2-7;

FIG. 10 is a longitudinal sectional view of the tip portion of theinitiation device shown in FIGS. 5-7, wherein arrows and broken linesdepict the relationship between current flow, magnetic fields and plasmagenerated during discharge of the initiation device;

FIG. 11 is a combined block, diagrammatic and schematic view of ainitiation system, in accordance with the present invention,particularly adapted for use in connection with an internal combustionengine, such as that used on conventional automobiles; and

FIG. 12 is a detailed schematic diagram of the currently preferred formof one of the electronic distribution systems shown in FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is concerned with improving fuel combustionefficiency by increasing the energy density of the medium which is usedto initiate the combustion of the fuel; this is achieved by producing aplasma which has an energy density nearly approaching or exceeding theenergy density produced by combustion of the fuel itself, yet requiresan electrical energy input for production thereof of only a few percentof the energy resulting from the combustion of the fuel.

Obviously, there are limitations on the amount of energy which may beexpended in bringing about combustion of the fuel. Because of therelative inefficiency of internal combustion engines, however, someadditional energy may be devoted to initiating combustion if sufficientgains in combustion efficiency are realized. For example, assume themaximum amount of energy which can be used to create initiation is givenby E_(i) and the required energy for initiating the leanest fuel mixtureis given by:

    (1) E.sub.i /V.sub.i

where V_(i) is the volume of the initiating discharge. In order tomaximize the value of E_(i) /V_(i), it becomes necessary to minimizeV_(i) since E_(i) cannot be increased beyond a predetermined value. Thepresent invention comprises, in part, recognition of the fact that V_(i)may be minimized by minimizing the time required for the delivery of theenergy E_(i) from an energy source to the initiation discharge. In orderto minimize the delivery time of the energy E_(i), a unique energydelivery system is provided in which an initiation capacitor C_(i) isdisposed adjacent the combustion fuel and is coupled by a transmissionline to a storage capacitor C_(s). For purposes of a simple theoreticalexplanation of the invention reference is now made to FIG. 1 wherein theelectrical characteristics of an initiating device constructed inaccordance with the present invention are generally indicated within thebroken line 20. The initiating device 20 includes a capacitive portionC_(i), an inductive portion L_(i), a resistive portion R_(i), and aspark gap indicated between the terminals 22 which is in series with theinductive portion L_(i) and resistive portion R_(i) but is in parallelwith the capacitive portion C_(i).

The initiating device 20 is coupled through a switch 24 and transmissionlines 26 having an inherent inductance L_(i) to power supply 28 whoseconstruction will be discussed later in more detail. Assuming now thatthe initiating device 20 is disposed in an area adjacent a fuel whosecombustion is to initiated, such as gasoline within the combustionchamber of an internal combustion engine, the switch 25 is switched tothe open position thereby causing the power supply 28 to chargecapacitor C_(s) to the desired voltage which will be somewhat greater inmagnitude than the voltage needed to initiate discharge of the device20. Switch 24 is then closed which causes the charge on capacitor C_(s)to be transferred to capacitor C_(i) thereby charging the latter untilthe breakdown voltage of device 20 is reached at which time capacitorC_(i) discharges to produce a high energy plasma jet which initiatescombustion of the adjacent fuel. It can be appreciated that the solepossible control over the timing of the discharge of device 20 rests inthe timing of the closure of switch 24, consequently, the time necessaryfor the breakdown of device 20 and initiation of the plasma jet, plusthe time need for the completion of fuel combustion by the plasma jetmust be short in comparison to the time required for substantial changesto take place in the combustion chamber. By making the capacitor C_(i)an integral part of the initiating device 20, the time required to.[.charge.]. .Iadd.discharge .Iaddend.the device 20 to the breakdownlevel whereby to produce a plasma jet is minimized.

Since the capacitor C_(i) is made an integral part of the device 20, itis necessary to minimize the physical space volume occupied by suchcapacitor. By charging capacitor C_(i) to the necessary voltage levelwithin a relatively short time period, typically on the order of a fewmicroseconds, insulating materials may be used in the construction ofcapacitor C_(i) which have a relatively high dielectric constant, suchas water. The determination of the discharge time of the device 20predetermines the maximum values for inductance L_(t) and capacitorC_(s).

Typically, the capacitor C_(i) is charged in approximately 10microseconds or less, and preferably in about 1.5 microseconds, which inturn dictates a value for L_(t) that can best be met by employing acoaxial transmission cable, and a coaxial construction for theinitiating device 20.

The total power produced by the initiating device 20 is given by thefollowing formula:

    Power=R.sub.i I.sup.2 +L.sub.i I+L iII

where I is the current and the dot notation is a time derivative. TheR_(i) I² component represents ohmic heating which is normally achievedin prior art type devices. However, the last two components L_(i) I andL_(i) II respectively represent additional power resulting from theplasma produced and the magnetic power being stored in the circuit; noneof the known prior art devices produces substantial power from theselast two mentioned components. The maximum current delivered by thedevice 20 is given by the equation: ##EQU1## where V represents thevoltage at which energy is stored in capacitor C_(i). Since the magneticpressure P at a radius r from the center of the inner conductor of theinitiating device 20 is given by: ##EQU2## .Iadd.the current dischargedbetween the electrodes is given by: .Iaddend. ##EQU3## and the energystored in the capacitor C_(i) is given by:

    E=1/2C.sub.i V.sup.2

it follows that the maximum magnetic pressure P max is: ##EQU4##consequently, it is imperative to minimize L_(i) in order to maximizethe magnetic pressure P. In order to make L_(i) small, the capacitorC_(i) is located integral with the initiating device and the innerelectrode comprises a relatively large diameter outside the plasmachamber. While the overall inductance L_(i) must be small. .[.Themagnetic density.]. .Iadd.That portion of the inductance.Iaddend.finally associated with the plasma itself must be as large aspossible and for this reason the radius of the inner conductor of theinitiating device 20 is made small within the plasma chamber.

Referring now to FIG. 3, an initiating device, previously generallydesignated in FIG. 1 by the numeral 20, includes a high voltageelectrode 30 and comprises a unitary member manufactured from a suitableelectrically conductive material as by machining. Electrode 30 includesa cylindrically shaped rear portion 32 electrically connected to thehigh voltage plate 34 of a transient storage capacitor generallydesignated at 36, and a forward portion 38 which includes a cylindricalrod shaped member or shank 39 having a diameter substantially less thanthat of the rear portion 32. The forward portion 38 of the device 20 isprovided with an annular flange 40 having a diameter marginally greaterthan that of the shank 30 and terminates in an elongate tip 42symmetrically rounded at the outer extremity thereof. The diameter ofthe tip 42 may be slightly less in magnitude than the diameter of theshank 39.

The initiating device 20 further includes a second electrode 44 ofunitary construction comprising an electrically conductive materialsuitably formed into a cylindrically shaped forward section 46circumscribing the forward portion 38 of the electrode 30 which includesa ring shaped cavity 48 in the outer end thereof defining an annularface 50 extending perpendicular to the base of the forward portion 38and axially concentric with respect to the latter. Essentially theentire forward portion 38 of electrode 30 is disposed within the cavity48 and extends longitudinally outward to a point transversely alignedwith the outer rim edge 52 of the forward section 46. The rear section54 of the second electrode 44 is also cylindrically shaped but possessesa diameter less than that of the forward section 46 and circumscribes amajor part of the rear portion 32 of the electrode 30. The base of therear section 54 is suitably electrically connected to the ground plate56 of the storage capacitor 36. Plates 34 and 56 are coupled with asuitable source of electrical energy (which will be discussed later inmore detail) by a coaxial cable schematically indicated by the nuneral58.

Electrodes 30 and 44 are insulated from each other by a layer ofinsulation 60 comprising any of various dielectrics such as water, oil,glycerene, or suitable solid material. The insulation 60 will include arelatively thin sleeve 62 thereof circumscribing the shank 39 andextending between the flange 40 and face 50, it should be noted herethat although the plates 34 and 56 are shown herein as circular inshape, any geometry thereof may be employed and in fact, as will becomelater apparent, may be folded in order to minimize the space displacedthereby. In any event, it is important that the plates forming thecapacitor portion of the device be located as close as possible to theabove-mentioned forward portions of the device forming the firing tip inorder to minimize the inductance in the resulting discharge circuit.

Another form of the initiating device 20 shown in FIG. 4 is similar inconstruction to the embodiment shown in FIGS. 2 and 3 but isdistinguishable therefrom in several respects. First, the forwardportion 64 of the high voltage electrode 30 is provided with a shank 66whose outer free extremity is spaced longitudinally inward from theplane formed by the outer peripheral edge or rim 68 of the forwardsection 70 of the second or ground electrode 44. The shank 66 includesan annular flange 72 similar to the flange 40, which terminates in aconically shaped tip 74. The forward section 70 of the second electrode44 includes a dish shaped face 76 partially defining one end of thecombustion cavity 78 and circumscribing the forward portion 64 of thehigh voltage electrode. The initiating devices shown in FIGS. 3 and 4are essentially identical in all other respects.

Attention is now directed to FIGS. 5-7 wherein still another form of theinitiating device is depicted. The device in FIGS. 5-7 comprises aunitary, elongate body of insulating dielectric, such as cast ceramic,having a main portion 80 and a sleeve portion 82 formed integral withthe main portion 80 on one end of the latter. Main portion 80 is definedby a plurality of radial folds forming longitudinally extending fins 84having a star shaped cross-section as best seen in FIG. 7. One end ofthe main portion 80 opposite the sleeve portion 82 is essentially open,as is the interior are a therewithin, while the opposite the sleeveportion 82. A suitable electrically conductive end thereof is enclosedby a shoulder 86 circumscribing inner covering 90, applied as bymetallization, covers essentially the entire inner surface of the mainbody portion 80, while a similar outer covering 92 is applied to theexterior surface of the fins 84 and shoulder 86. It may be necessary forease of manufacturing to also apply metallization to the exteriorsurface areas of the sleeve portion 82 which may be later removed as bymachining. Inner and outer coverings 88 and 90 respectively, areelectrically insulated from each other by the dielectric comprising mainbody portion 80, and in effect, form capacitor plates similar to plates34 and 56 discussed with reference to the device shown in FIGS. 3 and 4.

A pair of cylindrical lugs 92 and 94 are respectively joined as bybrazing to the inner and outer coverings 88 and 90 adjacent the open endof the main body portion 80, and provide corresponding high voltage andground terminals for the device. The high voltage portion of the devicefurther includes a cylindrically shaped shank 96 formed fromelectrically conductive material surrounded by the sleeve portion 82,one end of the shank 96 being joined, as by brazing, to the innerelectrical covering 88, the opposite end thereof terminating in apointed, circularly shaped tip 98. The shank 96 may be provided with abore 100 extending longitudinally therethrough from the end thereofadjacent the open interior areas of the main body portion 80 to a pointadjacent the tip 98. The bore 100 will accommodate expansion of theshank 96 during the brazing thereof to the inner coating 88. It is to benoted here that other suitable dielectric, insulative materials may beused in place of ceramic for body and sleeve portions 80 and 82, such aswater, isopropyl alcohol, or oil in which case a casing generallyconforming to the body and sleeve portions 80 and 82 may be provided forcontaining such liquids therein.

FIGS. 8 and 9 depict detailed views of two preferred forms of tips andthe currently known optimum geometrical design parameters therefor. Inthe case of the conically shaped pointed tip shown in FIG. 8, such tipincludes a thickness of material presenting a flat face 102 forming anangle A with respect to the longitudinal axis of the shank 96 which maybe between 0 and 45 degrees. The forward face 104 of the tip is inclinedrearwardly from a central apex 106 and may form an angle B with respectto an axis extending normal to the longitudinal axis of shank 96 whichoptimally is within the range of 15 to 90 degrees. The length "1" willbe determined by the previously discussed angles and the requirements ofthe particular application of the initiating device. In some cases, itmay be desirable to form the exterior of the shoulder 86 (and conformingouter covering 90) in an annular bevel 108, the interior edge of whichis radially spaced from the circumference of the sleeve portion 82. Theexterior face of the bevel 108 will preferably form an angle C withrespect to a normal from the longitudinal axis of the shank 96 which isapproximately equal to angle "D". The tip shown in FIG. 9 is similar tothat shown in FIG. 8 but is provided with a rounded forward face 110having a radius r, the rear face 112 of which is inclined forwardly andforms an angle D with respect to an axis normal to the longitudinal axisof the shank 96 which is preferably in the range of 0 to 45 degrees.

Attention is now directed to FIG. 10 in which the formation of plasma atthe tip of the initiating device is depicted during discharge thereof.Although a tip configuration is depicted similar to that shown in FIGS.6 and 8, it is to be understood that the description below also appliesto the other tip configurations disclosed herein and equivalentsthereof.

The initial step in creating a discharge of the initiating deviceinvolves steadily and rapidly charging the capacitive portion of thedevice (e.g. plates 34 and 56 in FIGS. 3 and 4) using a later discussedhigh voltage pulsed power supply. As previously indicated, charging ofthe capacitive portion will be performed within approximately 10microseconds, and preferably in about 1.5 microseconds. When suchcapacitive portion is charged to a sufficiently high voltage, electricalbreakdown occurs between an outer edge 114 of the tip 98 and the groundelectrode 116. Preferably, the capacitive portion will be charged to apotential of between 30 to 100 kilovolts. In the case of a device of thetype depicted in FIGS. 3 and 4, initial breakdown may comprise a"streamer" of electrical discharge current occurring between the annularflanges 40 and 72, and the interior surface areas of the side walls ofthe corresponding forward sections 46 and 70. However, as the currentindicated by the arrow 118 flowing through the shank 96 to the tiprapidly increases, the breakdown current flow immediately shifts to apath between the outer edge 114 of the area of the ground electrode 116circumscribing the shank 96 and generally parallel to the latter. Thisshift in breakdown current flow is a result of the fact that theimpedance between the high voltage and ground portion of the device isat a minimum value along a line between the outer edge 114 and theground electrode 116 due to the back EMF produced around the shank 96 bythe current 118 flowing therethrough.

The resulting breakdown current flow .[.is.]. .Iadd.may be .Iaddend.inthe form of a cylindrically shaped .[.sheet.]. .Iadd.sheath.Iaddend.indicated by the arrows 120 which completely circumscribes theshank 96 and is insulated from the latter by the sleeve portion 82;simultaneously, the flow of current 118 in the shank 96 produces acylindircal ring-shaped .[.electromagnetic.]. .Iadd.magnetic.Iaddend.field around the shank 96, the direction of .Iadd.the.Iaddend.corresponding magnetic flux lines being indicated at 122, inaccordance with the well known right hand rule. The resultingelectromagnetic field 122 functions to exert .[.an axially inward.]..Iadd.a radially outward.Iaddend.pressure on the .[.sheet.]..Iadd.sheath of .Iaddend.current flow 120 thereby tending to.[.confine.]. .Iadd.move .Iaddend.the latter .Iadd.outwardly .Iaddend.toproduce the well known linear .Iadd.inverse .Iaddend.pinch effect. Asthe current flow 118 increases, the discharge .[.sheet.]. .Iadd.sheath.Iaddend.current flow 120 likewise increases which .[.tends to forcecurrent flow 120 radially outwardly away from the shank 96, however, theelectromagnetic field 124 continues to confine the radial expansion ofthe current flow 120.]. .Iadd. causes increased joule heating in thedischarge plasma .Iaddend.thereby increasing the .Iadd.thermal.Iaddend.pressure and energy density of the current flow 120. As the.Iadd.current flow 118 through shank 96 and the .Iaddend.dischargecurrent flow 120 .[.continues.]. .Iadd.continue .Iaddend.to increasestill further in magnitude, .Iadd.the increasing inverse pinch magneticpressure due to the circumferential magnetic field 122 around shank 96and the increasing thermal pressure of plasma discharge 120 combine tourge discharge 120 .Iaddend..[.a second electromagnetic field (notshown) similar to that indicated by flux lines 122, but opposite incircumferential direction thereto, is created by the current flow 120which urges the latter.]. radially outward away from the shank 96. Thedischarge .[.sheet.]. current flow 120 continues to increase in energydensity and radially expands to the successive positions indicated bythe arrows 124, 126 and 128 until the diameter of the cylindricaldischarge sheet exceeds that of the tip 98 to allow the point that thecurrent emanates from the tip 98 to shift from the outer edges 114thereof to the forward face 130 thereof, whereby the emanating dischargecurrent forms an annular "umbrella" discharge shape. When the discharge.[.sheet of.]. current 120 expands past the edges 114 of the tip 98, thedischarge is free to shift axially forward, toward the left in FIG. 10,and eventually assumes a path indicated by the arrows 132 longitudinallyaligned with the shaft 96, whereby the discharge is delivered forwardlyto a fuel to be ignited in an area, such as a combustion chamber, towardthe left as shown in FIG. 10.

The high energy current .[.sheet.]. .Iadd.sheath .Iaddend.discharge, ofcourse, ionizes the atmosphere surrounding the shank 96 and tip 98 toproduce a high energy plasma thereat. As a result of the .[.confining.].forces applied to the discharge by the resultant electromagnetic fieldand rapid pressure and energy build-up, the plasma is delivered to thefuel in a slingshot or jet-like action. Because of the rapid delivery ofenergy to the tip 98 and geometrical configuration of the electrodes,the power of the plasma jet delivered to the fuel to ignite the lattermay exceed the power to used to charge the capacitive portion of thedevice by .[.an order to fifty times or more..]. .Iadd.many orders ofmagnitude. .Iaddend.

Depending on the particular geometry of the tip and the electricalpotential to which the capacitive portion of the device is charged, thedevice is advantageously discharged within approximately 1.2 to about 60nanoseconds, and preferably within 1.2 to about 2 nanoseconds. The rateof discharge will affect the energy density and geometry of theresulting plasma jet; the shorter discharge times producing a jet ofhigh energy density and narrow, linear geometry while longer dischargetimes result in a jet of somewhat lower energy density having dispersedgeometry. The .[.relative.]. rapid .[.discharge.]. .Iadd.combustion.Iaddend.rate of the combustion initiating device of the presentinvention is due in part to the fact that the tip 98 is longitudinallyspaced from, and is circumscribed by, the ground electrode 116, therebydefining a relatively large volume of space which is ionized by the highvoltage between the electrodes. Thus, a large volume of space becomeselectrically .[.superconductive.]. .Iadd.conductive .Iaddend.(due toionization) just prior to discharge.

.[.As is apparent from the foregoing description, electromagnetic fieldsfunction to confine the plasma discharge during formation thereof andit.]. .Iadd.It .Iaddend.is not necessary to provide side wallscircumscribing the tip portion of the device as shown in the embodimentsof FIGS. 3 and 4 in many applications. The walls surrounding the tip doserve to desirably reduce the overall resistance of the dischargecircuit, however, the need to employ such sidewalls to achieve optimumresults will be governed by numerous design considerations involved in aspecific application.

Attention is now directed to FIGS. 11 and 12, wherein an initiationsystem is depicted employing the initiating device forming a part of thepresent invention, which is particularly suited for use with aconventional internal combustion engine, such as that used inautomobiles.

As disclosed in FIG. 11, the initiating system is particularly adaptedfor use with a four cylinder engine, however, as will become apparentlater, the invention is equally suitable for use with an engine havingany number of combustion chambers. Broadly, the initiating systemcomprises a primary power source indicated within the broken line 134, ahigh voltage pulse generator 136, an essentially conventional electricaldistributor diagrammatically represented by the numeral 138, a spark gapdevice 140, a standard ignition coil 142, a high energy storagecapacitor 144, and a plurality of electronic distribution circuits, eachindicated in block form by the numeral 146 in FIG. 11, and shown in moredetail in FIG. 12.

Power source 134 comprises an ordinary 12 or 24 volt storage battery 148coupled in parallel relationship with a conventional charging device150, such as an alternator mechanically driven by the automobile'sengine, and is further coupled with a pair of output lines 152 and 154.The high voltage pulse generator 136 derives power from the power source134 via branch lines 156 and 158 which are respectively connected tooutput lines 152 and 154. Each of the inputs of distribution circuits146 are likewise coupled across the output lines 152 and 154 and inparallel relationship to the high voltage pulse generator 136 bydistribution lines 160 and 162. The input of distributor 138 is coupledto the power source 143 by line 164. Distributor 138 is conventional indesign and includes an output terminal corresponding to each of the fourengine cylinders, which are operably coupled to corresponding outputlines 166 which lines are respectively coupled to the trigger inputs ofrespectively corresponding ones of electronic distribution circuits 146.Each of the output lines 166 is also respectively coupled throughcorresponding diodes 174 to line 182 which forms the input of ignitioncoil 142. Ignition coil 142 may comprise a coil of conventional designordinarily employed in automobile engine electrical systems, or may bealternately comprise a shunt type inductor, since such coil merelyfunctions in the present application as a means of controlling thetiming of the delivery of electronic pulses, rather than to initiatefiring as in conventional designs. The output of coil 142 is coupled byline 184 to the trigger terminal 186 of the spark gap device 140.

Spark gap device 140 comprises an enclosed, pressure tight housing of asuitable geometric configuration, such as a cylinder, and is filled witha suitable gas, such as air which is pressurized above the atmosphericpressure level. Spark gap device 140 further includes first and secondspaced apart electrodes 188 and 190 respectively forming an air gaptherebetween located proximal to the trigger terminal 186. Terminal 190is coupled to ground 192, while terminal 188 is coupled via line 194 tothe negative output line 196 of the high voltage pulse generator 136,the positive output line 198 of the latter mentioned generator beingconnected to ground 200.

High voltage pulse generator 136 may comprise a conventional design ofthe SCR power converter type having a constant SCR trigger voltage ofapproximately 15,000 to 50,000 volts, and will be designed to charge thehigh voltage storage capacitor 144 to approximately 30 to 40 KV at arepetition rate of approximately 10 pulses per second. High energystorage capacitor 144 may be of a ceramic construction and willpreferably have a rating of approximately 100 KV to assure long life andreliability. One plate of the storage capacitor 144 is coupled with thecombination of the pulse generator 136 and spark gap device 140 whilethe other plate of capacitor 144 is coupled in series with each of theelectronic distribution circuits 146 by line 202. One side of a resistor204 is coupled with line 202 between capacitor 144 and circuits 146,while the other side of resistor 202 is coupled to ground 206.

Each of the electronic distribution circuits 146 has a pair of inputlines 208 and 210 respectively coupled to the distribution lines 162 and160 thereby placing each of the circuits 146 in parallel relationshipwith each other. The distribution circuits 146 each essentially comprisea variable time, power one-shot multivibrator of a conventional designsuch as that shown in IEEE, volume 12:7, pages 25 and 26.

Referring momentarily now to FIG. 12 in particular, the distributioncircuit 6 includes an SCR 212 (silicon controlled rectifier) having itsanode coupled through a diode 214 to line 208 while its gate is coupledto line 166. One main terminal of a TRIAC 216 is coupled throughresistors 218, 220 and capacitor 222 between line 202 and line 224 whichforms the ground portion 224 of a circuit connecting each of theinitiating devices (schematically indicated within the broken lines 226in FIG. 11). The other main terminal and the gate of TRIAC 216 arerespectively coupled through resistors 228 and 230 to line 202 and theground portions 224. The input line 210 is coupled to the cathode of SCR212, while a capacitor 232 is connected between input line 210 and thegate of TRIAC 216. A high voltage delivery line 234 is connected to line202 and forms the high voltage portion of a coaxial cable coupling thedistribution circuit 146 with the corresponding initiating devices 226which communicates with the corresponding engine cylinders.

As shown in FIG. 11, each of the initiating devices 226 comprises acapacitive portion indicated by the capacitor 236, a high voltageelectrode 238, a ground electrode 240 and a spark gap between electrodes238 and 240 indicated at 242.

Turning now to a description of the operation of the initiation system,power is delivered from the power source 134 to the distributor 138 aswell as to the pulse generator 136, via output lines 152 and 154. Thehigh voltage pulse generator has a direct current output ofapproximately 5 milliamps and charges the storage capacitor 144 toapproximately 50 KV. Voltage in line 164 is selectively coupled to theoutput lines 166 of the distributor 138 in a predetermined, timedsequence in the ordinary manner. As the automobile's engine mechanicallyrotates a rotor within the distributor 138, lines 166 are sequentiallycoupled with line 164, and the resulting firing signal is deliveredthrough line 182 to the ignition coil 142 which functions in the presentinvention to impose a time delay on the delivery of such signal to thetrigger terminal 186; the values of the various components will beselected in a manner such that the capacitor 144 is charged to thedesired level prior to the delivery of a firing signal to the terminal186.

Assuming now that the capacitor 144 is fully charged and one of theinitiating devices 226 is about to be fired, a control signal deliveredto trigger terminal 186 induces breakdown of the spark gap 187 withinthe spark gap device 140, thereby producing a firing spark betweenterminals 188 and 190 which couples the capacitor 144 to the ground 192.At this point, the capacitor 144 discharges into line 202 with aresulting current flow being delivered to each of the distributioncircuits 146 and the corresponding high voltage delivery lines 234.Simultaneously with the charging of capacitor 144, the firing signalproduced by distributor 138 is delivered by one of the output lines 166which have been energized and corresponds to the cylinder to be fired,to the trigger of SCR 212. SCR 212 then functions to activate the TRIAC216 which is operative to couple the ground portion 224 associated withthe cylinder about to be fired to ground potential through line 244,thereby permitting the storage capacitor 144 to release energy storedtherein through the high voltage line 234 of the cylinder about to befired. Energy delivered through line 234 is delivered to the capacitiveportion 236 of the initiating device 226. When the capacitive portion of236 of the initiating device 226 is charged to a prescribed level, whichcharging is completed within approximately 1.5 microseconds, electricalbreakdown occurs in the gap 242 resulting in the discharge of thecapacitive portion 236 which fires the device 226 by producing a plasmajet that initiates fuel within the cylinder to be fired.

From the foregoing, it is apparent that the initiating device andinitiation system of the present invention not only provide for thereliable accomplishment of the object of the invention but do so in aparticularly simple yet highly effective manner. It is to be understoodthat the initiating device of the present invention may be employed innumerous applications for initiating the combustion of various types offuels, including nuclear fuels. Those skilled in the art may makevarious modifications or additions to the preferred embodiment chosen toillustrate the invention without departing from the gist and essence ofthe present contribution to the art. Accordingly, it is to be understoodthat the protection sought and to be afforded hereby should be deemed toextend to the subject matter claimed and all equivalents thereof fairlywithin the scope of the invention.

What is claimed is:
 1. A device for generating a high energy plasma jetfor initiating combustion of fuel, comprising:a first electrodeincluding a rod shaped member and a tip on one extremity of said rodshaped member; .[.and.]. a second electrode electrically insulated fromsaid first electrode and including an annular portion circumscribing thelongitudinal axis of said rod shaped member, said tip beingsubstantially spaced along said longitudinal axis from said annularportion of said second electrode, said tip and said annular portiondefining an annular space therebetween across which electrical currentmay flow to produce an annularly shaped electrical discharge forinitiating combustion of said fuel, the longitudinal spacing betweensaid tip and said annular .[.position.]. .Iadd.portion .Iaddend.beingsufficient to allow said discharge to generate .[.a generallycylindrical.]. .Iadd.an .Iaddend.electromagnetic field .[.surroundingsaid discharge and sufficient in strength to temporarily radiallyconfine.]. .Iadd.for urging .Iaddend.said discharge .Iadd.radiallyoutward from said longitudinal axis; and means continuous with saidfirst and second electrodes for temporarily storing a quantity ofelectrical energy therein sufficient to produce said electricaldischarge, said device having an inherent inductance sufficiently low toresult in the discharge of the stored quantity of electrical energyacross said annular space within 60 nanoseconds .Iaddend..
 2. The deviceof claim 1, wherein said first and second electrodes are disposedconcentric with respect to said longitudinal axis of said rod shapedmember.
 3. The device of claim 2, wherein said tip includes a conicallyshaped outer surface, the outer periphery of said surface being spacedessentially equidistant from said longitudinal axis of said rod member.4. The device of claim 3, wherein said conically shaped surface forms anangle with respect to a plane extending normal to said longitudinal axisof said rod shaped member, said angle being in the range of between 15and 90 degrees.
 5. The device of claim 3, wherein said tip includes anannularly shaped, flat face contiguous with said conically shapedsurface and adjacent the outer periphery of said tip, said annularlyshaped flat face forming an angle with respect to said longitudinal axisof said rod shaped member between 0 and 45 degrees.
 6. The device ofclaim 2, wherein said tip includes a hemispherically shaped outersurface.
 7. The device of claim 2 wherein said annularly shaped portionof said second electrode includes a first annularly shaped, essentiallyflat section circumscribing said rod shaped member and immediatelyadjacent the latter, and a second annularly shaped, essentially flatsection circumscribing said first section, said first and second flatsections forming an angle with respect to each other in the range of 0to 45 degrees.
 8. The device of claim 2, wherein said rod shaped memberincludes a bore extending longitudinally therethrough.
 9. The device ofclaim 2, wherein said annularly shaped portion of said second electrodeforms a disk shaped surface circumscribing the circumferential sidewalls of said rod shaped member.
 10. The device of claim 2, wherein saidfirst electrode further includes a tip on one extremity of said rodshaped member, said tip including an annular flange extending radiallyoutward beyond the circumferential side walls of said rod shaped member,and an outer, elongate tip portion longitudinally aligned with said rodshaped member contiguous with said flange.
 11. The device of claim 2,wherein said annular portion of said second electrode is disposedadjacent one extremity of said first electrode, said rod shaped memberincluding a cylindrically shaped intermediate section and an annularlyshaped flange on .[.the opposite.]..Iadd., said one .Iaddend.extremitythereof, the diameter of said flange being greater than the diameter ofsaid intermediate section of said rod.
 12. The device of claim 11,wherein said .[.opposite.]. .Iadd.one .Iaddend.extremity of said rodshaped member terminats in a conically shaped surface. .[.13. The deviceof claim 2, including means formed integral with said first and secondelectrodes for temporarily storing a quantity of electrical energytherein sufficient to produce a high energy plasma jet for initiatingcombustion of said fuel..].
 14. The device of claim .[.13.]..Iadd.1.Iaddend., wherein said storing means comprises a capacitorhaving a pair of spaced-apart, electrical storage plates, one of saidplates being contiguous to and coupled with said one electrode, theother of said pair of plates being contiguous to and coupled with saidsecond electrode.
 15. The device of claim 14 wherein said pair ofelectrical storage plates have a dielectric material interposedtherebetween, said dielectric material being selected from the groupconsisting of ceramic, water, oil, glycerene, or isopropyl alcohol. 16.The device of claim 15, wherein said rod shaped member is disposedbetween said tip and said pair of capacitor plates, and each of saidcapacitor plates of said pair thereof are of generally star shaped crosssection.
 17. The device of claim 14, wherein said one capacitor plate ofsaid pair thereof is connected to the opposite extremity of said rodshaped member.
 18. The device of claim 1, including a layer ofelectrically insulative material surrounding the cylindrical sidewallsof said rod .[.shape.]. .Iadd.shaped .Iaddend.member and interposedbetween said annular portion of said second electrode and said rodmember.
 19. The device of claim 18, wherein said tip is essentiallycircular in cross section, the circular periphery of said tip extendingradially outward beyond the cylindrical sidewalls of intermediatesections of said rod member, whereby the diameter of said tip exceedsthe diameter of said intermediate sections of said rod member.
 20. Thedevice of claim 19, wherein the outside diameter of said layer ofinsulative material is less in magnitude than the diameter of said tip.21. An improved device for initiating combustion of fuel in a combustionchamber using a high energy plasma jet, comprising:first and secondelectrodes communicating with said combustion chamber and defining.[.a.]. .Iadd.an .Iaddend.annular discharge gap therebetween acrosswhich .Iadd.a preselected quantity of .Iaddend.electrical energy may betransferred, .Iadd.said preselected quantity of electrical energy beingsufficient in magnitude to produce a high energy plasma jet resulting inthe initiation of combustion of said fuel, .Iaddend.said first andsecond electrodes being configured to produce .[.a generallycylindrical.]. .Iadd.a current flow which creates an.Iaddend.electromagnetic field for .[.radially confining the transfer ofelectrical energy between said electrodes during said transfer;.]..Iadd.urging the transfer of electrical energy between said electrodesradially outward; and, .Iaddend. means contiguous with said first andsecond electrodes and immediately adjacent said combustion chamber fortemporarily storing .[.a.]. .Iadd.said preselected .Iaddend.quantity ofelectrical energy therein .[.sufficient in magnitude to create said highenergy plasma jet.]., said storing means being adapted for electricallycoupling with a source of electrical power and electrically connectedwith each of said first and second electrodes.Iadd., said device havingan inherent inductance sufficiently low to result in the discharge ofsaid preselected quantity across said discharge gap within 60nanoseconds.Iaddend..
 22. The device of claim 21 wherein:said first andsecond electrodes are concentrically disposed with respect to each otherabout a longitudinal axis, said second electrode being annular in shapeand circumscribing portions of said first electrode, said firstelectrode being elongate and including a tip portion on one end thereof,said tip portion being spaced from said second electrode along saidlongitudinal axis, said discharge gap being defined by an annular spacesurrounding said first electrode between said tip portion and saidsecond electrode.
 23. The device of claim 22, wherein said tip portionis essentially circular in cross section and the periphery of said tipportion extends radially outward from said longitudinal axis beyond thelongitudinal sidewalls of said first electrode.
 24. The device of claim23, wherein said second electrode forms an annular cavity surroundingessentially the entire length of said first electrode.
 25. The device ofclaim 24, wherein said annular cavity is dish shaped.
 26. The device ofclaim 22, wherein said second electrode extends radially outward fromsaid longitudinal axis, the interior perimeter of said second electrodebeing radially spaced from said first electrode.
 27. The device of claim22, including a layer of electrical insulative material surrounding atleast parts of said first electrode including said portions thereof andextending from said tip portion toward the other end of said firstelectrode.
 28. The device of claim 21, wherein said first electrode isessentially cylindrical in shape.
 29. The device of claim 28, whereinsaid .Iadd.first .Iaddend.electrode includes a bore extendinglongitudinally therethrough.
 30. The device of claim 21 wherein saidstoring means comprises a capacitor including a pair of spaced apartelectrical energy storage plates respectively coupled with said firstand second electrodes.
 1. The device of claim 30, wherein each of saidstorage plates is essentially star shaped in cross-section.
 32. Thedevice of claim 30, wherein said pair of storage plates are eachsymmetrically disposed about said longitudinal axis.
 33. The device ofclaim 32, wherein said first electrode includes a tip portion on one endthereof distal from said second electrode, said tip portion beinggenerally conical in shape.
 34. The device of claim 32, wherein saidpair of storage plates are respectively formed integral with said firstand second electrodes.
 35. A system for sequentially initiatingcombustion of a plurality of predefined quantities of fuel,comprising:high voltage generating means adapted to be operably coupledwith a source of electrical energy for producing a high electricalvoltage; electrical energy storage means operably coupled with said highvoltage generating means for storing a predetermined quantity electricalenergy; a plurality of combustion initiation devices respectivelyassociated with said plurality of said predefined quantities of fuel andspaced distal from said energy storage means, each of said devicesincluding a capacitive portion for storing said predetermined quantityof electrical energy therein and an electrode portion formed integralwith said capacitive portion, each said devices being operable to.Iadd.discharge said predetermined quantity of electrical energy throughsaid electrode portion within approximately 60 nanoseconds, saidpredetermined quantity of electrical energy being sufficient inmagnitude to .Iaddend.produce a high energy plasma jet for initiatingcombustion of the corresponding quantity of fuel, the electrode portionof each of said devices comprising a first electrode including a rodshaped member having a tip on one end thereof and a second electrodeelectrically insulated from said first electrode and including anannular portion circumscribing the longitudinal axis of said rod shapedmember, said tip being substantially spaced from said annular portion,said tip and said annular portion defining an annular space therebetweenacross which electrical current may be transferred to produce an.[.annularly shaped.]. electrical discharge, the longitudinal spacingbetween said tip and said annular portion being sufficient to allow saiddischarge to generate .[.a generally cylindrical.]. .Iadd.an electricalcurrent flow producing an .Iaddend.electromagnetic field .[.envelopingsaid discharge, said field being.]. sufficient in strength .[.totemporarily radially restrain said discharge whereby to increase theenergy density of said discharge.]. .Iadd.for moving said discharge,said predetermined quantity of electrical energy being sufficient toproduce said magnetic field.Iaddend.; and timing control means operablycoupled with said electrical energy storage means and with each of saidinitiation devices for selectively coupling said electrical energystorage means with said initiation devices in a predetermined timed.[.sequency.]. .Iadd.sequence .Iaddend.whereby to sequentially deliversaid predetermined quantity of electrical energy from said storage meansto individual ones of said capacitive portions of said initiationdevices.
 36. The system of claim 35, wherein:said second electrode isdisposed concentric with respect to said first electrode about saidlongitudinal axis, and said first electrode includes a layer ofelectrically insulative material covering said rod shaped member andextending between said tip and said annular portion of said secondelectrode.
 37. The system of claim 36, wherein said rod shaped member isessentially circular in cross section, the diameter of said tip beinggreater in magnitude than the diameter of intermediate sections of saidrod shaped member between said tip and said annular portion of saidsecond electrode.
 38. The system of claim 37, wherein said tip isgenerally conical in shape.
 39. The system of claim 36, wherein saidannular portion of said second electrode extends radially outward fromsaid longitudinal axis, the inner periphery of said annular portionbeing spaced from the longitudinal sidewalls of said rod shaped member.40. The system of claim 36 wherein said insulative material is selectedfrom the group consisting of glass or ceramic.
 41. The system of claim35, wherein said capacitive portion of each of said devices comprises apair of electrically conductive, spaced apart plates defining acapacitor and respectively contiguous with said first and secondelectrodes.
 42. The system of claim 41, wherein each of said plates issymmetrically disposed about said longitudinal axis, said plates beingrespectively electrically connected to said annular portion of saidsecond electrode and to the opposite extremity of said rod shapedmember.
 43. The system of claim 41, including a layer of dielectricsubstance interposed between said plates.
 44. The system of claim 43,wherein said dielectric substance is one selected from the groupconsisting of water, oil, glycerine, isopropyl alcohol or ethyleneglycol.
 45. The system of claim 41, wherein each of said platescomprises a plurality of sections, each of said sections extendingessentially radially outward from said longitudinal axis.
 46. The systemof claim 35, wherein said high voltage generation means is capable ofproducing an output of at least approximately 15,000 volts.
 47. Thesystem of claim 35, where said high voltage generating means comprises apulse type voltage generator.
 48. The system of claim 35, wherein saidhigh voltage generating means includes an output for delivering highvoltage electrical energy thereto, said storage means being electricallycoupled to said output of said generating means, said timing controlmeans comprising:distribution circuit means coupled with each of saidinitiation devices and with said storage means for selectivelydistributing electrical energy from said storage means to thecorresponding one of said initiation devices.
 49. The system of claim48, wherein distribution circuit means comprises a plurality ofelectrical circuits respectively associated with said initiationdevices, each of said circuits comprising an electronic switch connectedbetween said storage means and the respectively associated initiationdevice, and an electronic trigger operably coupled with said switch forcontrolling the latter.
 50. The system of claim 49, wherein said timingcontrol means further includes:first control means operably coupled withsaid storage means for controlling the discharge of electrical energystored in said storage means from the latter to said distributioncircuit means, and second control means operably coupled with said firstcontrol means and with each of said electrical circuits for selectivelydelivering a control signal simultaneously to a selected one of saidelectrical circuits and to said first control means.
 51. The system ofclaim 50, wherein said first control means comprises a pair of spacedapart electrical terminals defining a spark gap therebetween and a thirdelectrical terminal coupled with said second control means for inducingelectrical breakdown of the medium between said pair of electricalterminals.
 52. The system of claim 50, wherein said second control meanscomprises:a first electrical terminal adapted to be coupled with asource of electrical power, a plurality of electrical terminalsrespectively coupled with said electrical circuits, and means forselectively coupling said first electrical terminal with one of saidplurality of electrical terminals.
 53. The system of claim 50, whereinsaid timing control means further includes an inductor operably coupledbetween said first and second control means.
 54. The system of claim 35,wherein said high voltage generating means is provided with an input andthere is further provided:a source of electrical power operably coupledwith said high voltage generating means.
 55. The system of claim 54,wherein said source of electrical energy comprises a battery and meansoperably coupled with said battery for recharging the latter.
 56. Thesystem of claim 35, including a coaxial electrical cable operablycoupled between each of said initiation devices and said timing controlmeans, said cable comprising an inner and outer conductor, said innerand outer conductors being operably coupled with the capacitive portionof the corresponding initiation device. .Iadd.
 7. Apparatus forinitiating combustion of fuel, comprising:first and second electrodesdefining a gap across which a preselected quantity of electrical energymay be discharged, the magnitude of said preselected quantity ofelectrical energy being sufficient to form a high energy plasma forinitiating combustion of said fuel; and capacitor means substantiallycontiguous with said first and second electrodes for storing saidpreselected quantity of electrical energy, the inductance of saidelectrodes and said capacitor means being sufficiently low to allow saidpreselected quantity of electrical energy to be discharged across saidgap within 60 nanoseconds..Iaddend. .Iadd.58. The apparatus of claim 57,wherein said first and second electrodes are symmetric about a commonaxis. .Iaddend. .Iadd.59. The apparatus of claim 58, wherein saiddischarge gap is annular in shape and is disposed coaxial with andlongitudinally along said common axis. .Iaddend. .Iadd.60. The apparatusof claim 57, wherein said capacitor means includes first and secondstorage plates respectively connected to said first and secondelectrodes. .Iaddend. .Iadd.61. The apparatus of claim 57, includingmeans coupled with said capacitor means for charging said capacitormeans with said preselected quantity of electrical energy in less thanapproximately 10 microseconds. .Iaddend. .Iadd.62. The apparatus ofclaim 58, wherein said preselected quantity of electrical energy storedin said capacitor means produces an electrical current through saidelectrodes sufficient in magnitude to create an inverse pinch electricaldischarge across said gap and between said electrodes, and to develop amagnetic pressure for moving said discharge radially outward from saidaxis, the quantity of said electrical current being given by ##EQU5##.Iaddend. .Iadd.63. A device for initiating combustion of a gaseousair-fuel mixture in a combustion chamber using a high energy plasma,comprising:first and second electrodes symmetric about a reference axisand defining an electrical discharge gap; and means coupled with saidelectrodes for storing a preselected quantity of electrical energysufficient in magnitude to produce an electrical discharge between saidelectrodes across said gap, said discharge resulting in the initiationof combustion of said gaseous air-fuel mixture, said electrodes and saidstoring means defining an electrical discharge circuit in said device,said discharge circuit having an inherent inductance and beingconfigured to minimize said inherent inductance and thereby maximize themagnitude of magnetic power generated by the current flowing in saiddischarge circuit, the inherent inductance of said discharge circuitbeing sufficiently low to result in the transfer of preselected quantityof electrical energy from said storing means to the electrical dischargein less than approximately 60 nanoseconds. .Iaddend. .Iadd.64. Thedevice of claim 63, wherein:said first and second electrodes and saiddischarge gap are coaxial, said discharge gap being annular in shape andextending longitudinally along said axis, said preselected quantity ofelectrical power and said magnetic power being sufficient in magnitudeto create an inverse pinch electrical discharge between said electrodesacross said gap. .Iaddend.